The bursal cytokine gene expression and apoptosis were compared in vaccinated chickens with either live or immune-complex infectious bursal disease virus (IBDV) vaccines with or without virulent IBDV challenge. The cytokine gene expressions were evaluated at 5 and 12 day-post-challenge (DPC). The apoptotic marker Caspase-3 was determined by IHC on collected bursae, thymus, spleen, and kidneys at 12 DPC. A significantly decreased bursal cytokine levels were observed in the all-vaccinated birds except for IL-6 in the classic IBD vaccines at 5DPC. A significant upregulation of the IL-2 was observed in the live IBD vaccinated birds. No significant differences in the bursa and thymus Caspase-3 positive cells. However, splenic and renal apoptosis was significantly higher in the live IBD vaccine groups. Results indicate that both vaccine types reduce the IBDV-induced bursal proinflammatory cytokines and apoptosis. However, classic IBD vaccines failed to clear the challenge virus or reduce splenic and renal apoptosis.
Keywords: Apoptosis; Caspase-3; Cytokines; IBDV; Immune-complex; Vaccine.
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